Embodiments of the present disclosure relate generally to treating the surface of a rotatable component. More specifically, the present disclosure includes an apparatus and method for treating a rotatable component such as a turbine spacer or a turbine wheel.
In a turbine apparatus such as a steam or gas turbine, various turbine sections typically include substantially circular “spacers” positioned between different turbine wheel stages. Each of these spacers may be coaxial with opposing nozzle diaphragms of the turbine apparatus. Although a turbine apparatus typically includes a set amount of clearance between a spacer and an opposing nozzle diaphragm, some spacers and nozzle diaphragms may contact each other while the turbine operates. Certain types of stress experienced by the turbine spacer can cause “stress risers” to form on the surface of the spacer.
Removing stress risers typically requires an on-site repair to reduce or remove the stress risers from the surface of the spacer. Conventionally, stress risers can be removed by rotating the spacer to a particular position, manually grinding the stress riser with a grinding tool, and then rotating the spacer to reach other stress risers if needed. The manual treatment of stress risers can be a costly and time-consuming process. In addition, human errors during the treatment can create non-uniform turbine spacers or other types of workpieces. In other situations, stress can be intentionally introduced to a spacer or other rotating component by “peening” the surface of the component. Peening can be implemented by similar manually implemented techniques, and therefore may incur similar costs.